This important result needs to be remembered in two ways:
Result 1:
Result 2:
Result 2 is most commonly used when factorising:
Eg1:
These kind of questions are easily spotted as they:
· only have 2 terms
· always have subtract sign
· always have square numbers
· usually have even powers
Always first re-write the question as a difference of two squared terms before factorising:
Eg2:
Eg3